So basically you can say `if I have 5 parts of water to 2 parts of clorox, and I have 6 gallons of water, how much clorox do I have'.
You can set that up by setting the two fractions equal to each other:
\[\frac{5}{2} = \frac{6}{x}\]
You can flip that so it's a little easier to solve for \(x\) -- just remember to flip both sides!
\[\frac{2}{5} = \frac{x}{6}\]